<html>
	<head>
		<style>
		*{padding:0;margin:0;}
		#box1{
		    width:500px;
		    height:100px;
		    background:blue;
		    position:absolute;
		    z-index:100;
		}
		#box2{
		    width:800px;
		    height:200px;
		    background:red;
		    position:absolute;
		    top:20px;
		    left:50px;
		}
		#box3{
		    width:1000px;
		    height:300px;
		    background:green;
		    position:absolute;
		    top:40px;
		    left:100px;
		    z-index:-1;
		}
		</style>
	</head>
	<body>
		<div id="box1">1
		</div>
		<div id="box2">2
		</div>
		<div id="box3">3
		</div>
	</body>
</html>